High silica content substrate such as for use in thin-film battery

ABSTRACT

A high silica content substrate, such as for a thin-film battery, is provided. The substrate has a high silica content, such as over 90% by weight silica, and is thin, for example less than 500 μm. The substrate may include a surface with a topography or profile that facilitates bonding with a coating layer, such as a coating of an electrochemical battery material. The high silica content substrate may be flexible, have high temperature resistance, high strength and/or be non-reactive. The substrate may be suitable for use in the high temperature environments used in many chemical deposition or formation processes, such as electrochemical battery material formation processes.

BACKGROUND

The disclosure relates generally to high-silica content substratematerials, and specifically to high-silica content substrate materialsfor deposition of reactive materials and/or for use in high temperaturematerial deposition environments, such as thin-film battery materialdeposition. Silica soot may be generated by a process, such as flamehydrolysis. The silica soot may then be sintered to form a fully orpartially sintered high silica content substrate. Thin-film batteries,such as thin-film rechargeable lithium batteries, contain thin-filmlayers of cathode material, anode material, separator material,electrolyte material and current collector material.

SUMMARY

One embodiment of the disclosure relates to an electrochemical batteryassembly including a high silica content substrate. The substrateincludes a first major surface, a second major surface opposite thefirst major surface, at least 90% SiO₂ by weight, an average thicknessbetween the first major surface and the second major surface of lessthan 500 μm and a minimum dimension orthogonal to the thickness that isless than 100 m and greater than 1 mm. The electrochemical batteryassembly includes a first layer of a first battery material bonded tothe first major surface of the substrate. The first battery material isone of a cathode material, an anode material, an electrolyte and acurrent collector material.

An additional embodiment of the disclosure relates to an assemblyincluding a substrate and a coating. The substrate includes a firstmajor surface and a second major surface opposite the first majorsurface. The substrate includes at least 99% by weight silica, and thesubstrate is formed from a glass of (SiO₂)_(1-x-y).M′_(x)M″_(y)composition, where either or both of M′ and M″ is an element, dopant, orsubstitution, which may be in an oxide form, or combination thereof, oris omitted, and where the sum of x plus y is less than 1. The substrateincludes an average thickness between the first major surface and thesecond major surface of less than 500 μm and a width and a length thatare each less than 100 m and greater than 2 mm. The first major surfaceincludes a plurality of raised features and a plurality of recessedfeatures, and at least some of the raised features extend from thesurface a distance of at least 10 angstroms further than the recessedfeatures. The coating is positioned directly on the first major surfacesuch that an inner surface of the coating contacts the first majorsurface. The coating is a contiguous coating that extends over at leastone recessed feature and at least one raised feature and is contiguousfor at least 1% of the width and the length of the substrate.

An additional embodiment of the disclosure relates to a fused quartzsubstrate including a first major surface having a surface area greaterthan 1 mm² and a second major surface opposite the first major surface.The substrate includes an outer perimeter surface extending between thefirst major surface and the second major surface. The substrate includesat least 99% by weight silica, has an average thickness between thefirst major surface and the second major surface of less than 500 μm andhas a width and a length that are each less than 100 m and greater than1 mm. The substrate includes a first group of a plurality of raisedelongate features formed in the first major surface and extending in thedirection of the width. Each raised elongate feature of the first grouphas a length and a width, and the length is at least ten times largerthan width, and the width of each elongate feature of the first group isbetween 10 mm and 2 μm. The substrate includes a second group of aplurality of raised elongate features formed in the first major surfaceand extending in the direction of the length. At least some of theraised elongate features of the second group intersect a raised elongatefeature of the first group. Each raised elongate feature of the secondgroup has a length and a width, and the length is at least ten timeslarger than width. The width of each elongate feature of the secondgroup is between 10 mm and 2 μm. At least some of the raised elongatefeatures of the first group and of the second group extend from thesurface a distance of at least 10 angstroms beyond the lowest portion ofthe first major surface. The surface area of the first major surface isat least 1.5 times the area of the cross-sectional shape defined by theouter perimeter surface of the substrate.

Additional features and advantages will be set forth in the detaileddescription that follows, and, in part, will be readily apparent tothose skilled in the art from the description or recognized bypracticing the embodiments as described in the written description andclaims hereof, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary, and areintended to provide an overview or framework to understand the natureand character of the claims.

The accompanying drawings are included to provide a furtherunderstanding and are incorporated in and constitute a part of thisspecification. The drawings illustrate one or more embodiment(s), andtogether with the description serve to explain principles and theoperation of the various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sectional view of a thin-film battery including a highsilica content substrate according to an exemplary embodiment.

FIG. 2 is a schematic representation from a perspective view of asubstrate according to an exemplary embodiment.

FIG. 3 is a 3D nano-scale representation of a measured profile of asurface of substrate according to an exemplary embodiment.

FIG. 4 is a 2D nano-scale representation of a measured profile of thesurface of FIG. 3.

FIG. 5 is a schematic representation from a perspective view of asubstrate according to another exemplary embodiment.

FIG. 6 is a 3D micro-scale representation of a measured profile of asurface of a substrate according to an exemplary embodiment.

FIG. 7 is a schematic representation from a perspective view of asubstrate according to another exemplary embodiment.

FIGS. 8 and 9 are schematic representations from a perspective view ofsubstrates manufactured according to exemplary embodiments.

DETAILED DESCRIPTION

Referring generally to the figures, a high silica content substrate foruse in the formation of an assembly with reactive materials or materialsprocessed at high temperatures, such as thin-film battery materials, areshown and described. In addition, systems and processes for forming suchsubstrates and assemblies are shown and described. The high silicasubstrate discussed herein provides a combination of various propertiesthat are believed to provide significant improvements over conventionalsubstrate materials currently used in the construction of thin-filmbatteries, such as thin-film lithium-based batteries. For example, thehigh silica substrate discussed herein has a very high softeningtemperature (e.g., greater than 650 degrees C., 700 degrees C., 800degrees, etc.) which allows the high silica substrate to resistdeformation or damage during high temperatures used during processing orformation of battery materials during battery assembly, such as duringhigh temperature crystal formation. For example, to form a thin-filmbattery as discussed herein, battery materials may be deposited onto ahigh silica substrate at relatively low temperatures, and then exposedto high temperatures to form desired crystal structures during sinteringor annealing processes. In addition, the high silica substrate discussedherein has a very low coefficient of thermal expansion and one which isrelatively close to the coefficient of thermal expansion of batterymaterials. Thus, the low coefficient of thermal expansion of thesubstrate discussed herein provides for material coatings to bedeposited on the substrate in a tight fit with a high level of bondingto the substrate. It is believed that this tight fit and high level ofbonding is particularly advantageous in thin-film battery applicationsin which the density of battery materials bonded to the substrate isincreased relative to conventional substrate materials and theconventional surface structures resulting in an increased energy densityof the battery formed using the substrates discussed herein.

In addition to the advantages during battery materialdeposition/processing, the high silica substrate discussed herein has avariety of properties that provides additional advantages. For example,one or both major surfaces of the high silica substrate discussed hereinmay have a rough surface or a series of elongate raised ridges orrecesses that increase the substrate surface area. This increasedsurface area may facilitate increased bonding with an adjacent layer ofbattery material, and the recesses between raised ridges may alsoprovide an extra volume (compared to a flat or polished substrate) inwhich battery material may be contained resulting in higher energydensity. Thus, the unique surface morphology of the substrate discussedherein may be particularly effective to increase energy density of abattery utilizing the substrate.

In addition, the high silica substrate discussed herein is both thin(e.g., less than 500 μm in thickness, less than 200 μm in thickness,etc.) and has relatively high strength (at least considering its lowthickness). These two properties allow for formation of a battery inwhich more of the total volume of the battery is formed from the activebattery materials and less volume needs to be occupied by the substrate,and thus increases the overall energy density of the battery. Inaddition, the high silica substrate discussed herein is highly flexibleproviding a substrate that may be useful in flexible multilayeredassemblies, such as flexible thin-film batteries.

In addition, the substrate discussed herein provides these properties inconjunction with a high purity (e.g., high silica content), thatprovides a non-reactive, non-corrosive and high electrical resistanceinsulating substrate that is believed to function well as a supportstructure for reactive and conductive materials, such as thin-filmbattery materials. In addition, the substrate discussed herein providesa battery support structure able to withstand a wide voltage range(e.g., voltages within a window from 0 volts to 5.5 volts). Thus, it isbelieved that the high silica substrate discussed herein provides acombination of one or more property that provides superior functioningin various layered assemblies, such as thin-film battery assemblies,compared to conventional substrate materials, such as mica, siliconwafers, silica wafers, gallium nitride, sapphire, polymers, etc.Specifically conventional substrate materials tend be relatively thick,inflexible, irregularly shaped and expensive as compared to the highsilica substrate discussed herein.

Referring to FIG. 1, an electrochemical battery assembly (e.g., anelectrochemical cell, electrochemical device, etc.), shown as thin-filmor solid-state battery 10, is shown. In general, battery 10 includes oneor more layer of battery materials (e.g., cathode materials, anodematerials, electrolyte materials, current collector materials, etc.)bonded to and/or supported by a high silica content substrate, shown assilica sheet 12. As will be explained in greater detail herein, silicasheet 12 provides various material and physical properties that providefor improved performance relative to conventional battery substratematerials, such as mica. Further, it should be understood that whilemany of the specific embodiments discussed herein relate to silica sheet12 as a battery substrate, in other embodiments silica sheet 12 may beused as a substrate for any number of other applications, and inparticular for other devices, systems or processes in which a thinsubstrate is used to receive layers or coatings of materials. Forexample, silica sheet 12 may also be used for carbon nanotube formation.

Referring generally to FIGS. 1 and 2, silica sheet 12 includes a firstmajor surface, shown as upper surface 14, and a second major surface,shown as lower surface 16, that is on the opposite side of sheet 12 fromupper surface 14. Silica sheet 12 includes an outer perimeter surface,shown as sidewall surface 18, that extends between outer most edges ofupper surface 14 and lower surface 16.

In the embodiment shown in FIG. 1, battery 10 includes a first layer ofa first battery material, shown as current collector 20, in contact withand/or bonded to upper surface 14 and also bonded to lower surface 16.Battery 10 includes a second layer of a second battery material, shownas cathode material 22, in contact with and/or bonded to an outersurface of current collector 20, and a third layer of a third batterymaterial, shown as electrolyte material 24, in contact with and/orbonded to an outer surface of cathode material 22. Battery 10 includes afourth layer of a fourth battery material, shown as anode material 26,in contact with and/or bonded to an outer surface of electrolytematerial 24, and a fifth layer of a fifth battery material, shown ascurrent collector 28, in contact with and/or bonded to an outer surfaceof anode material 26. Thus in this embodiment, the electrochemicallayers of battery 10 are supported by sheet 12.

In a specific embodiment, each layer of battery material may alsoinclude a section that is directly bonded to upper surface 14 and/orlower surface 16, as shown in FIG. 1 at region 32. Bonding of each layerof battery material to sheet 12 at region 32 may facilitate structuralintegrity of battery 10 by providing a direct coupling of each layer ofbattery material to sheet 12. It should be understood that while battery10 shows a particular ordering of battery material layers, battery 10may include any suitable ordering of battery material layers that allowsbattery 10 to function as a battery.

In the specific embodiment shown, electrolyte material 24 also acts as aseparator material located between cathode 22 and an anode 26 that keepsthese two layers electrically isolated from each other. In variousembodiments, battery 10 may include an additional outer protective layer30 that surrounds the various layers of battery 10 leaving only smallportions of current collectors 20 and 28 and the adjacent portions ofsheet 12 accessible for electrical connection to a device powered bybattery 10.

In various embodiments, the battery materials of layers 20, 22, 24, 26and 28 may be any suitable battery material. In various embodiments, thecathode material of cathode 22 is a lithium based cathode material, suchas lithium-nickel materials, lithium oxides, lithium phosphates, lithiumsulfur, lithium mixed metal phosphates, lithium mixed metal oxides ofstructures (e.g., layered, olivine, spinel structures and combinationsthereof). In specific embodiments, the cathode material may beLiNiMnCoO₂, LiCoO₂, LiMn₂O₄, LiFePO₄, etc. In various embodiments, theanode material of anode 26 is at least one of graphite, other forms ofcarbon, Li₄Ti₅O₁₂, an alloy of tin/cobalt and silicon-carbon materials.In various embodiments, electrolyte 24 is a solid electrolyte that alsoacts as spatial separator preventing electrical contact directly betweenthe cathode to the anode. In a specific embodiment, electrolyte 24 islithium phosphorus oxynitride (LiPON). In other embodiments, battery 10may include a separator layer that is distinct and separate from theelectrolyte material, and in such embodiments, the separator layer maybe a non-liquid material such as zirconia or garnet. In variousembodiments, the current collectors 20 and 28 may be any suitablecurrent collector material, including copper materials, aluminummaterials, aluminum/carbon materials, carbon nanotubes, fibers, etc.

The various layers of battery materials may be deposited using anysuitable deposition method including, pulsed laser deposition, magnetronsputtering, chemical vapor deposition, MOCVD, sol-gel processing andothers. In various embodiments, sheet 12 is a glass sheet formed from asilica soot sheet that is masked and annealed to create a 3D surfacestructure (discussed below) that is capable of handling the hightemperatures need to deposit and/or anneal the anode, cathode andelectrolyte materials.

In various embodiments, thin-film battery 10 discussed herein may beused in a wide variety of applications, in which the various physicalproperties discussed herein (e.g., high energy density, high power,thin, minimal foot print, flexibility, strength, etc.) are advantageous.For example, battery 10 may be used in thin portable devices such asportable consumer electronics and medical devices. In some embodiments,battery 10 may be used in implantable medical devices such asdefibrillators and neural stimulators. In some embodiments, battery 10may be used with “smart” cards, RFID tags and wireless sensors. Incertain embodiments, battery 10 can serve to store energy collected fromsolar cells and other energy harvesting devices.

Referring to FIGS. 1 and 2, upper surface 14 and/or lower surface 16 ofsheet 12 includes a non-flat or non-polished surface texture or profilethat includes a plurality of raised features 40 and recessed features42. In various embodiments, raised features 40 and recessed features 42have irregular profile shapes in cross-section as shown in FIGS. 1 and2. In other embodiments, raised features 40 and recessed features 42have a consistent or repeating profile shape in cross-section.

In various embodiments, at least some of the raised features 40 extendfrom the surface of sheet 12 a distance of at least 10 angstroms furtherthan the recessed features 42, such as at least 50 angstroms, such as atleast 100 angstroms, such as at least 500 angstroms. In someembodiments, raised features 40 extend from the surface of sheet 12 adistance of at least 1 μm beyond the lowest portion of upper surface 14(e.g., the lowest of the lowest recessed portion), and more specificallyat least 2 μm beyond the lowest recessed portion. In variousembodiments, upper surface 14 and/or lower surface 16 are primarilyunpolished such that the surface has a surface roughness Ra of greaterthan 1.5 angstrom for a 40 μm by 30 μm area thereon, which may be asubsection of the total area of surface. In another embodiment, however,upper surface 14 and/or lower surface may be polished such that thatsurface roughness Ra is less than 1.5 angstrom for a 40 μm by 30 μm areasection.

In various embodiments, the surface texture provided by raised features40 and recess features 42 may provide a surface that facilitates bondingto various coating layers (e.g., layers of battery material). Forexample, raised features 40 and recessed features 42 may increase thesurface area of upper surface 14 and/or lower surface 16 (as compared toa flat or polished surface) providing additional area for adjacentcoating layers to be bonded to sheet 12. Further, it is believed thatraised features 40 and recessed features 42 may provide for a morerobust connection between sheet 12 and the adjacent layer by formingsomewhat of interlocking engagement between the adjacent surfaces.

As shown best in FIG. 1, at least one layer coated on sheet 12 (e.g.,current collector 20 in the exemplary embodiment in FIG. 1) ispositioned directly on the major surfaces of sheet 12 such that an innersurface of the coating layer contacts upper surface 14 and/or lowersurface 16. In this embodiment, the first coating layer is a contiguouscoating layer that contacts upper surface 14 and/or lower surface 16 onat least one recessed feature 42 and at least one raised feature 40. Inone embodiment, one or more coating layer is contiguous for at least 1%of the width and/or length of the substrate, and more specifically, atleast 10% of the width and/or length of the substrate. In suchembodiments, the innermost coating layer is contiguous extending over aplurality of recessed features 42 and raised features 40. In a specificembodiment, the innermost coating layer is a contiguous layer thatcovers at least 25% of the area of upper surface 14 and/or lower surface16, at least 50% of the area of upper surface 14 and/or lower surface 16and more specifically at least 70% of the area of upper surface 14and/or lower surface 16. In specific embodiments in which sheet 12 is abattery substrate, at least 90% of the area of upper surface 14 and/orlower surface 16 is covered by at least one layer of battery material.

In various embodiments, the presence of raised features 40 and recessedfeatures 42 provides upper surface 14 and/or lower surface 16 with anarea that is greater than the area of the same shaped surface that ispolished smooth. In specific embodiments, the surface area of uppersurface 14 or of lower surface 16 is greater than the area of across-section shape defined by sidewall 18. In specific embodiments, thesurface area of upper surface 14 or of lower surface 16 is at least 1.5times greater than the area of a cross-section shape defined by sidewall18, and more specifically is at least 2 times greater than the area of across-section shape defined by sidewall 18. Further, in thoseembodiments in which the coating layers are battery layers, theincreased surface area relative to a flat or polished surface area mayallow for an increased battery energy density. In specific embodiments,the area of upper surface 14 and/or of lower surface 16 is greater than1 mm², and more specifically is greater than 2 mm².

Referring to FIG. 3 and FIG. 4, examples of an unpolished surface ofsheet 12 are shown according to various exemplary embodiments. Forexample, FIG. 3 shows a 3D representation of a 40 μm by 30 μm area ofupper surface 14 of sheet 12 according to an exemplary embodiment. FIG.4 shows a 2D representation of nanostructure of the same substratesample as FIG. 3. Both FIGS. 3 and 4 show the raised and recessedfeatures 40, 42 of surface 14 on a nano-scale, where upper surface 14 isnon-flat or unpolished.

Referring back to FIG. 1 and FIG. 2, sheet 12 has a thickness, shown asT1, that generally is the distance between opposing portions of uppersurface 14 and lower surface 16. In some embodiments discussed herein T1is a specific thickness between two opposing points along upper surface14 and lower surface 16, and in other embodiments, T1 is an averagethickness between all opposing points along upper surface 14 and lowersurface 16. In some embodiments, sheet 12 has a thickness T1 of lessthan 500 μm, such as less than 250 μm, and in some such embodiments lessthan 50 μm. According to an exemplary embodiment, T1 is between 200 μmand 1 μm, specifically between 200 μm and 5 μm and more specificallybetween 150 μm and 5 μm. In a particularly thin embodiment, T1 isbetween 1 μm and 20 μm. Thus, according to these exemplary embodiments,sheet 12 is arranged as a particularly thin sheet of silica material.Such a thin sheet may be counter-intuitive for substrate manufacturersdue to the processes of cutting, grinding, lapping, and polishing, whichmay require or benefit from a greater thickness.

As shown in FIG. 1, the multi-layered assembly, shown as battery 10, mayhave a total thickness, shown as T2. As shown, T2 is the distancemeasured between opposing outermost surfaces of the battery assembly ina direction perpendicular to upper surface 14 and/or lower surface 16 ofsheet 12. In various embodiments, T2 is between 10 μm and 600 μm, andmore specifically between 20 μm and 200 μm. In various embodiments,sheet 12 is relatively thin relative to total thickness T2. In general,T1 is less than 60% of T2. In various embodiments, T1 is less than 10%of T2, specifically is less than 5% of T2 and more specifically is lessthan 1% of T2. In various embodiments in which the assembly supported bysheet 12 is a battery, decreasing the percentage of thickness (andconsequently volume) of the battery occupied by the substrate increasesthe energy density of the battery.

According to an exemplary embodiment, sheet 12 has a first minimumdimension D orthogonal to the thickness (e.g., width, length, minimumsurface dimension) and a second minimum dimension L orthogonal to thethickness and orthogonal to dimension D. In various embodiments, Dand/or L are each less than 100 m and greater than 1 mm, andspecifically are less than 5 m and greater than 2 mm. Such dimensionsmay be useful for battery applications and in conjunction with equipmentthat deposits layers of battery materials. In such embodiments, thevarious coating layers maybe shaped to cover all or substantially all ofsheet 12.

In various embodiments, sheet 12 may be formed in a variety of shapes asneeded for particular layered assemblies. For example, in at least somebattery applications, sheet 12 may be shaped to specifically conform toa shape within a device housing which in turn facilitates increasing theamount of battery energy within a particular volume of the devicepowered by the battery. In various embodiments, as shown FIG. 2, sheet12 has a cross-sectional shape defined by sidewall 18 that isnon-circular, and specifically is rectilinear. In other embodiments,sheet 12 may be circular in shape or polygonal in shape, and in yetother embodiments, sheet 12 may have an irregularly shaped sidewall 18that is shaped to conform to components and/or to fill otherwise emptyspace within a device housing.

As used herein, the term “substrate” generally refers to a substance,layer or material that may underlie something, or on which some processmay occur. For example, the substrate may be a top layer of amultilayered structure, an exterior layer, an internal layer, etc. Inthe embodiment, shown in FIG. 1, sheet 12 acts as an internal substratelayer.

In some embodiments, sheet 12 consists of at least 90% by weight, andspecifically at least 99% by weight, of a material of the composition of(SiO₂)_(1-x-y).M′_(x)M″_(y), where either or both of M′ and M″ is anelement (e.g., a metal) dopant, or substitution, which may be in anoxide form, or combination thereof, or is omitted, and where the sum ofx plus y is less than 1, such as less than 0.5, or where x and y are 0.4or less, such as 0.1 or less, such as 0.05 or less, such as 0.025 orless, and in some such embodiments greater than 1E⁻6 for either or bothof M′ and M″. In some embodiments, the substrate is highly pure fusequartz, such as at least 99.5% quartz, such as 99.9% quartz. Put anotherway, in some embodiments, the substrate is highly pure SiO₂, such as atleast 90% SiO₂, 95% SiO₂, 99% SiO₂, 99.5% SiO₂, such as 99.9% SiO₂. Incertain embodiments, sheet 12 is crystalline, and in some embodiments,sheet 12 is amorphous. In some embodiments, sheet 12 is a fused quartzmaterial. In one embodiment, sheet 12 is a fully sintered silica sheet.In another embodiment, sheet 12 is a partial sintered silica sheet. Inanother embodiment, sheet 12 is unsintered silica soot sheet.

In those embodiments in which sheet 12 is a substrate for a battery,such as battery 10, the high silica purity allows sheet 12 to beunreactive with the active electrochemical materials of battery 10. In aspecific embodiment in which cathode material 22 is a lithium basedcathode material, the high silica content of sheet 12 allows sheet toremain unreactive with the battery materials within a voltage range of0.1 V to 5.5 V, even at high charge and discharge levels up to 100 Clevels. In various embodiments, the high silica content of sheet 12allows sheet 12 to remain unreactive with the battery materials of thedifferent layers both during the high temperature deposition, sinteringor annealing of those materials and during charge and discharge cyclesof the battery, and in addition, the high silica content of sheet 12 mayalso allow sheet 12 to provide insulation between the battery materialsof the different layers.

In various embodiments, the high silica content of sheet 12 allows sheet12 to handle the reactive environments (both reducing and oxidizing) andhigh temperatures (600° C.-1200° C.) that are typically needed forannealing and crystallization of cathode, anode and/or electrolytematerials of battery 10. In one embodiment, annealing of the cathodematerial crystalizes the cathode material increasing energy density ofbattery 10. In various embodiments, sheet 12 has a high softening pointtemperature, that being greater than 700° C., such as greater than 800C, such as greater than 900° C., such as greater than 1000° C. Inaddition, sheet 12 has a low coefficient of thermal expansion, thatbeing less than 10×10⁻⁷/° C. in the temperature range of 50 C to 300° C.The high softening point of sheet 12 allows sheet 12 to withstand highprocessing temperatures, such as temperatures of between 600-1200° C.for depositing, sintering, annealing and/or crystallizing batterymaterials. The low coefficient of thermal expansion of sheet 12 providesstructural and dimensional stability to battery 10 with changes intemperature, as may occur during manufacturing of battery 10 or in useof battery 10.

In various embodiments, sheet 12 is a strong and flexible substratewhich may allow battery 10 to be flexible. In various embodiments, sheet12 is bendable such that the thin sheet bends to a radius of curvatureof at least 500 mm without fracture when at room temperature of 25° C.In specific embodiments, sheet 12 is bendable such that the thin sheetbends to a radius of curvature of at least 300 mm without fracture whenat room temperature of 25° C., and more specifically to a radius ofcurvature of at least 150 mm without fracture when at room temperatureof 25° C. Bending of sheet 12 may also help with roll-to-rollapplications, such as processing across rollers in automatedmanufacturing equipment, such as a battery manufacturing line. This mayallow formation using high throughput manufacturing techniques such asthose used in semiconductor processing.

In various embodiments, sheet 12 is a transparent or translucent sheetof silica glass. In one embodiment, sheet 12 has a transmittance greaterthan 90% and more specifically greater 95%. In various embodiments,sheet 12 also is light weight allowing a decrease in the total weight ofthe battery utilizing sheet 12. Further, sheet 12 has a relatively lowdensity compared to conventional battery substrate materials. Inaddition the high purity of sheet 12 is highly non-reactive such as 99%,and more preferably greater than 99.9%, for non-reactivity withelectro-active materials

Referring generally to FIG. 5, a high silica content substrate, shown assilica sheet 50, is shown according to an exemplary embodiment. Silicasheet 50 is substantially the same as sheet 12 except as discussedherein. In general, silica sheet 50 includes a first major surface,shown as upper surface 52, and a second major surface, shown as lowersurface 54. In the embodiment shown, sheet 50 includes intersectingelongate features 56 (e.g., raised elongate features, recessed elongatefeatures, grooves, ridges, channels, canals, etc.). In some embodiments,some or all of the elongate features 56 have a length that is at leastten times a width thereof. According to an exemplary embodiment, atleast some of the elongate features 56 have a width that is greater than2 μm and less than 10 mm, such as greater than 10 μm and less than 5 mm,such as greater than 50 μm and less than 2 mm. In one embodiment, widthof elongate features 56 is the distance between points on either side ofpeak that goes below average surface elevation. For such embodiments,texture of the surface 52 and 54 is at least in part formed by theintersecting elongate features 56, such as in addition to unpolishednanostructure as shown in FIGS. 2 and 3.

In some embodiments, elongate features 56 include a first group ofraised features 58 and a second group of raised features 60 that bothextend outward from upper surface 52. In various embodiments, lowersurface 54 includes raised features 58 and 60 similar to upper surface52. In one embodiment, raised features 58 and 60 form a pattern ofcrisscrossing elongate features. In the embodiment shown, raisedfeatures 58 generally extend in the direction of dimension L, and raisedfeatures 60 generally extend in the direction of dimension D, and inthis arrangement, raised features 58 and 60 intersect each other forminga grid like pattern. In a specific embodiment, raised features 58 arelinear features that are generally parallel to dimension L, and raisedfeatures 60 are linear features parallel to dimension D. However inother embodiments, raised features 58 and 60 may be at nonperpendicularangles relative to each and may be nonparallel to dimensions L and D,respectively, and in some embodiments, raised features 58 and 60 may benonlinear. Similar to raised features 40 (shown in FIG. 2), raisedfeatures 58 and 60 may extend a distance of at least 1 μm above thelowest point of the surface 52, specifically as at least 2 μm above, andmore specifically such as at least 5 μm above.

As shown in FIG. 6, a 3D micro-scale representation of the profile ofupper surface 52 of sheet 50 is shown according to an exemplaryembodiment. Control of the shape and orientation of the elongatefeatures may be achieved by laser sinter, as described herein. Theintersecting elongate features 56 may facilitate bonding with thedeposited battery layers as discussed herein.

Referring to FIG. 7, a high silica content substrate, shown as silicasheet 70, is shown according to an exemplary embodiment. Silica sheet 70is substantially the same as sheet 50 except as discussed herein. Sheet70 is circular in cross-sectional shape.

Referring now to FIGS. 8 and 9, soot sheets 80, 90 (e.g., sheet of SiO₂soot, quartz soot, a soot form of a glass or precursor thereof, such asany glass material described herein) are shown. In one embodiment sootsheets 80, 90 may be sintered and used as substrates as describedherein, and in another embodiment, soot sheets 80, 90 may be partiallysintered or unsintered and used as a substrate as discussed herein. Forexample, in various embodiments, soot of soot sheets 80, 90 may bepressed into a sheet having a low density, such as less than 1.5 g/cm³,such as less than 1 g/cm³, such as less than 0.5 g/cm³. FIGS. 8 and 9show lasers 82, 84, 92 (e.g., CO₂ lasers, greater than 100 Watt laser,greater than 200 W laser, less than 2000 W laser) at least partiallysintering and/or densifying the respective soot sheets 80, 90, which areextending from manufacturing equipment 86, 96 such as a soot depositionrotor, tread, wheel, roller, or other such equipment.

While other sintering devices may be used to achieve some embodiments,Applicants have discovered advantages with laser sintering in theparticular ways disclosed herein. For example, Applicants found thatlaser sintering may not radiate heat that damages surrounding equipmentor overheat and burn up the susceptor (e.g., platinum susceptor,graphite) which may be concerns with sintering via induction heating andresistance heating. Applicants found that laser sintering has goodcontrol of temperature and repeatability of temperature and may not bowor otherwise warp the ribbon, which may be concerns with flamesintering. In comparison to such other processes, laser sintering mayprovide the required heat directly and only to the portion of the sootsheet needing to be sintered. Laser sintering may not send contaminatesand gas velocity to the sintering zone, which may upset manufacturing ofthe thin sheets. Further, laser sintering is also scalable in size orfor speed increases.

According to an exemplary embodiment, a laser(s) 82, 84, 92 may bedirected by lenses (e.g., on ends thereof, spaced apart therefrom) toform a laser energy plane 88 (e.g., beam of rectangular cross-section),90, 98 to sinter the soot sheet to glass, such as to produce a ribbon ofhigh viscosity glass. Some embodiments of the process include fullysintering the soot sheet from low density soot sheet (e.g., 0.5 g/cm³)to fully sintered, such as having a density greater than 1.0 g/cm³, suchas greater than 1.5 g/cm³, such as greater than 2.0 g/cm³ (e.g., 2.2g/cm³) or more, such as by any of the above processes, and preferably bythe laser(s) 82, 84, 92.

Other embodiments include partially sintering the soot sheet 80 suchthat the soot sheet has a density greater than 0.5 g/cm³ and/or lessthan 2.2 g/cm³. Partially sintered soot sheets may hold together betterthan unsintered sheets, such as being able to be rolled on a spool(e.g., spool diameter of at least 1 in and/or no more than 12 in). Incontemplated embodiments, unsintered soot sheets or partially sinteredsoot sheets, of materials as described herein, may be used as endproducts, such as serving as substrates, layers, barriers, etc., such asto receive and support layers of battery materials or for otherpurposes. Likewise, glass substrates described herein may be used forpurposes other than for supporting layers of battery materials.

Referring to FIGS. 8 and 9, in some embodiments the process at leastpartially (e.g., fully) sinters columns or other shapes of glass ordensified soot through the soot sheet in selected patterns.Alternatively, masking may be used to isolate portions of the sootsheet, which may then be removed or otherwise sintered to creategeometry, such as a patterned profile for cathode deposition. Some suchselective and/or partial sintering may not be possible or may beextremely difficult with processes other than laser sintering. In someembodiments, use of a laser to sinter the edges of the soot sheet fullyor partially, just prior to removing the soot sheet from themanufacturing line (e.g., following deposition on a rotor) overcomesprocessing issues where edges or ends of the soot sheet may tear orcrack. This full or partial sintering of the edges prior to sheetremoval from the manufacturing line may strengthen the edge and inhibittearing or cracking.

In various embodiments, following the formation of a high silica sheetas shown in FIGS. 8 and 9, one or more coating or layer may be depositedonto the upper or lower surface of the silica substrate (such as sheets12, 50, 70, etc.). In various embodiments, the formation process relatesto formation of a battery such as battery 10 discussed above. In suchembodiments, a layer of battery material is deposited on to thesubstrate. In various embodiments, at least one of a cathode, anode orelectrolyte material is deposited on the substrate. In a specificembodiment, a cathode material is deposited, annealed and crystalizedonto the substrate.

As used herein, the silica (SiO₂) containing sheet may be a thin sheetformed from deposited silica soot, may also be a thin sheet of silicaglass formed by fully sintering the silica soot sheet, and may also be athin sheet of partially sintered silica soot. In various embodiments,the silica soot sheets disclosed herein are formed by a system thatutilizes one or more glass soot generating device (e.g., a flamehydrolysis burner) that is directed or aimed to deliver a stream ofglass soot particles on to a soot deposition plate. As noted above, thesilica sheets discussed herein may include one or more dopant. In theexample of a flame hydrolysis burner, doping can take place in situduring the flame hydrolysis process by introducing dopant precursorsinto the flame. In a further example, such as in the case of aplasma-heated soot sprayer, soot particles sprayed from the sprayer canbe pre-doped or, alternatively, the sprayed soot particles can besubjected to a dopant-containing plasma atmosphere such that the sootparticles are doped in the plasma. In a still further example, dopantscan be incorporated into a soot sheet prior to or during sintering ofthe soot sheet. Example dopants include elements from Groups IA, IB,IIA, IIB, IIIA, IIIB, IVA, IVB, VA, VB and the rare earth series of thePeriodic Table of Elements. In various embodiments, the silica sootparticles may be doped with a variety of materials, including germania,titania, alumina, phosphorous, rare earth elements, metals and fluorine.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order. Accordingly, where a method claim doesnot actually recite an order to be followed by its steps or it is nototherwise specifically stated in the claims or descriptions that thesteps are to be limited to a specific order, it is in no way intendedthat any particular order be inferred. In addition, as used herein, thearticle “a” is intended to include one or more than one component orelement, and is not intended to be construed as meaning only one.

It will be apparent to those skilled in the art that variousmodifications and variations can be made without departing from thespirit or scope of the disclosed embodiments. Since modifications,combinations, sub-combinations and variations of the disclosedembodiments incorporating the spirit and substance of the embodimentsmay occur to persons skilled in the art, the disclosed embodimentsshould be construed to include everything within the scope of theappended claims and their equivalents.

What is claimed is:
 1. An electrochemical battery assembly comprising: ahigh silica content substrate comprising: a first major surface; asecond major surface opposite the first major surface; at least 90% SiO₂by weight; an average thickness between the first major surface and thesecond major surface of less than 500 μm; and a minimum dimensionorthogonal to the thickness that is less than 100 m and greater than 1mm; and a first layer of a first battery material bonded to the firstmajor surface of the substrate, wherein the first battery material isone of a cathode material, an anode material, an electrolyte and acurrent collector material.
 2. The electrochemical battery assembly ofclaim 1, wherein the first battery material is a current collectormaterial, the electrochemical battery assembly further comprising: asecond layer of a second battery material bonded to the first layer,wherein the second battery material is one of a cathode material and ananode material; a third layer of a third battery material bonded to thesecond layer, wherein the third battery material is an electrolytematerial; a fourth layer of a fourth battery material bonded to thethird layer, wherein the fourth battery material is one of a cathodematerial and an anode material; and a fifth layer of a current collectormaterial bonded to the fourth layer.
 3. The electrochemical batteryassembly of claim 2, having a total thickness measured between opposingoutermost surfaces of the battery assembly in a direction perpendicularto the first major surface, wherein the thickness of the substrateaccounts for less than 60% of the total thickness of the batteryassembly.
 4. The electrochemical battery assembly of claim 2, whereinthe cathode material includes at least one of LiCoO₂, LiMn₂O₄LiFePO₄, Lisulfur, Li mixed metal phosphates, and Li mixed metal oxides, whereinthe anode material includes at least one of graphite, LiNiMnCoO₂,Li₄Ti₅O₁₂, an alloy of tin and cobalt and silicon-carbon materials,wherein the electrolyte material is lithium phosphorus oxynitride. 5.The electrochemical battery assembly of claim 4, wherein the substrateis nonreactive with the cathode material at voltages from 0.1 V to 5.5V.
 6. The electrochemical battery assembly of claim 1, wherein thesubstrate consists of at least 99% SiO₂ by weight, wherein the substrateis formed from a glass of (SiO₂)_(1-x-y).M′_(x)M″_(y) composition, whereeither or both of M′ and M″ is an element, dopant, or substitution,which may be in an oxide form, or combination thereof, or is omitted,and where the sum of x plus y is less than 1, wherein the substrate hasa thickness less than 250 μm.
 7. The electrochemical battery assembly ofclaim 6, wherein the substrate further comprises: a width and a lengththat are each less than 100 m and greater than 1 mm; an outer perimetersurface extending between the first major surface and the second majorsurface; a first group of a plurality of raised elongate features formedin the first major surface and extending in the direction of the width,wherein each raised elongate feature of the first group has a length anda width and the length is at least ten times larger than width, whereinthe width of each elongate feature of the first group is between 10 mmand 2 μm; and a second group of a plurality of raised elongate featuresformed in the first major surface and extending in the direction of thelength, wherein at least some of the raised elongate features of thesecond group intersect raised elongate features of the first group,wherein each raised elongate feature of the second group has a lengthand a width and the length is at least ten times larger than width,wherein the width of each raised elongate feature of the second group isbetween 10 mm and 2 μm; wherein at least some of the raised elongatefeatures of the first group and of the second group extend from thesurface a distance of at least 2 μm beyond a lowest portion of the firstmajor surface; wherein the surface area of the first major surface is atleast 1.5 times the area of the cross-sectional shape defined by theouter perimeter surface of the substrate.
 8. The electrochemical batteryassembly of claim 7, wherein the substrate bends to a radius ofcurvature of at least 500 mm without fracture when at room temperatureof 25° C., wherein the substrate has a softening point temperaturegreater than 700° C., wherein the substrate has a low coefficient ofthermal expansion less than 10×10⁷/° C. in the temperature range ofabout 50 to 300° C., thereby facilitating dimensional stability to thesubstrate during formation of the first battery material on thesubstrate.
 9. The electrochemical battery assembly of claim 7, whereinthe cross-sectional shape defined by the outer perimeter surface of thesubstrate is non-circular.
 10. The electrochemical battery assembly ofclaim 7, wherein the cross-sectional shape defined by the outerperimeter surface of the substrate is rectilinear.
 11. Theelectrochemical battery assembly of claim 1, wherein the substrate is afused quartz material.
 12. An assembly comprising: a substratecomprising: a first major surface; a second major surface opposite thefirst major surface; and at least 99% by weight silica, wherein thesubstrate is formed from a glass of (SiO₂)_(1-x-y).M′_(x)M″_(y)composition, where either or both of M′ and M″ is an element, dopant, orsubstitution, which may be in an oxide form, or combination thereof, oris omitted, and where the sum of x plus y is less than 1; wherein thefirst major surface comprises a plurality raised features and aplurality of recessed features, wherein at least some of the raisedfeatures extend from the surface a distance of at least 10 angstromsfurther than the recessed features; and a coating positioned directly onthe first major surface such that an inner surface of the coatingcontacts the first major surface, wherein the coating is a contiguouscoating that extends over at least one recessed feature and at least oneraised feature and is contiguous for at least 1% of the width and thelength of the substrate.
 13. The assembly of claim 12, wherein thecoating contiguously covers at least 25% of the first major surface. 14.The assembly of claim 13, wherein the coating is formed from a firstbattery material, wherein the first battery material is one of a cathodematerial, an anode material, an electrolyte material and a currentcollector material.
 15. The assembly of claim 14, wherein the firstbattery material is a cathode material, and the cathode material is atleast one of LiCoO₂, LiMn₂O₄LiFePO₄, Li sulfur, Li mixed metalphosphates, and Li mixed metal oxides.
 16. The assembly of claim 12,wherein: the substrate has an average thickness between the first majorsurface and the second major surface between 1 μm and 250 μm; thesubstrate bends to a radius of curvature of at least 500 mm withoutfracture when at room temperature of 25° C.; and the substrate has asoftening point temperature greater than 700° C., wherein the substratehas a low coefficient of thermal expansion less than 10×10⁻⁷/° C. in thetemperature range of about 50 to 300° C., thereby facilitatingdimensional stability to the substrate during formation of the coatingon the substrate; and a width and a length that are each less than 100 mand greater than 2 mm.
 17. The assembly of claim 12, wherein thesubstrate further comprises an outer perimeter surface extending betweenthe first major surface and the second major surface, wherein theplurality of raised and recessed features comprises: a first group of aplurality of raised elongate features formed in the first major surfaceand extending in the direction of the width, wherein each raisedelongate feature of the first group has a length and a width and thelength is at least ten times larger than width, wherein the width ofeach raised elongate feature of the first group is between 10 mm and 2μm; and a second group of a plurality of raised elongate features formedin the first major surface and extending in the direction of the length,wherein at least some of the raised elongate features of the secondgroup intersect a raised elongate feature of the first group, whereineach raised elongate feature of the second group has a length and awidth and the length is at least ten times larger than width, whereinthe width of each elongate feature of the second group is between 10 mmand 2 μm; wherein at least some of the raised features of the firstgroup and of the second group extend from the surface a distance of atleast 1 μm beyond the lowest portion of the first major surface; whereinthe surface area of the first major surface is at least 1.5 times thearea of the cross-sectional shape defined by the outer perimeter surfaceof the substrate.
 18. A fused quartz substrate comprising: a first majorsurface having a surface area greater than 1 mm²; a second major surfaceopposite the first major surface; an outer perimeter surface extendingbetween the first major surface and the second major surface; at least99% by weight silica; an average thickness between the first majorsurface and the second major surface of less than 500 μm; and a widthand a length that are less each than 100 m and greater than 1 mm; afirst group of a plurality of raised elongate features formed in thefirst major surface and extending in the direction of the width, whereineach raised elongate feature of the first group has a length and a widthand the length is at least ten times larger than width, wherein thewidth of each elongate feature of the first group is between 10 mm and 2μm; and a second group of a plurality of raised elongate features formedin the first major surface and extending in the direction of the length,wherein at least some of the raised elongate features of the secondgroup intersect a raised elongate feature of the first group, whereineach raised elongate feature of the second group has a length and awidth and the length is at least ten times larger than width, whereinthe width of each elongate feature of the second group is between 10 mmand 2 μm; wherein at least some of the raised elongate features of thefirst group and of the second group extend from the surface a distanceof at least 10 angstroms beyond the lowest portion of the first majorsurface; wherein the surface area of the first major surface is at least1.5 times the area of the cross-sectional shape defined by the outerperimeter surface of the substrate.
 19. The fused quartz substrate ofclaim 18, wherein the substrate has a thickness less than 250 μm,wherein the substrate bends to a radius of curvature of at least 500 mmwithout fracture when at room temperature of 25° C., wherein thesubstrate has a softening point temperature greater than 700° C.,wherein the substrate has a low coefficient of thermal expansion lessthan 10×10⁷/° C. in the temperature range of about 50 to 300° C.
 20. Thefused quartz substrate of claim 19 wherein the substrate is formed froma material of (SiO₂)_(1-x-y).M′_(x)M″_(y) composition, where either orboth of M′ and M″ is an element, dopant, or substitution, which may bein an oxide form, or combination thereof, or is omitted, and where thesum of x plus y is less than 1.